package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * 优惠券订单
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 沉梦听雨
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private SeckillVoucherServiceImpl seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private RedissonClient redissonClient;
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    // 导入lua脚本 确保原子性
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("secKill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    // 获取代理对象（事务）
    private IVoucherOrderService proxy;

    // 异步处理单线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    // PostConstruct注解：在类初始化之后执行，因为当这个类初始化好了之后，随时都是有可能要执行的
    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    // 用于线程池处理的任务
    // 当初始化完毕后，就会去从对列中去拿信息
    private class VoucherOrderHandler implements Runnable {
        private final String queueName = "stream.orders";
        @Override
        public void run() {
            while (true){
                try {
                    // 0.初始化stream
                    initStream();
                    // 1.获取消息队列中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1(本次查询的最大数量) BLOCK 2000(当没有消息时最长等待时间) STREAMS s1 >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明没有消息，继续下一次循环
                        continue;
                    }
                    // 订单信息不为空，解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    // 3.创建订单
                    createVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }
            }
        }
        public void initStream(){
            Boolean exists = stringRedisTemplate.hasKey(queueName);
            if (BooleanUtil.isFalse(exists)) {
                log.info("stream不存在，开始创建stream");
                // 不存在，需要创建
                stringRedisTemplate.opsForStream().createGroup(queueName, ReadOffset.latest(), "g1");
                log.info("stream和group创建完毕");
                return;
            }
            // stream存在，判断group是否存在
            StreamInfo.XInfoGroups groups = stringRedisTemplate.opsForStream().groups(queueName);
            if(groups.isEmpty()){
                log.info("group不存在，开始创建group");
                // group不存在，创建group
                stringRedisTemplate.opsForStream().createGroup(queueName, ReadOffset.latest(), "g1");
                log.info("group创建完毕");
            }
        }
        private void handlePendingList() {
            while (true) {
                try {
                    // 1.获取pending-list中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    // 2.判断订单信息是否为空
                    if (list == null || list.isEmpty()) {
                        // 如果为null，说明pending-list没有异常消息，结束循环
                        break;
                    }
                    // 订单信息不为空，解析数据
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    // 3.创建订单
                    createVoucherOrder(voucherOrder);
                    // 4.确认消息 XACK stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理pending-list订单异常", e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }
    }
    /*    // 阻塞队列
        private BlockingQueue<VoucherOrder> orderTasks =new  ArrayBlockingQueue<>(1024 * 1024);
        private class VoucherOrderHandler implements Runnable {
            @Override
            public void run() {
                while (true){
                    try {
                        // 1.获取队列中的订单信息
                        VoucherOrder voucherOrder = orderTasks.take();
                        // 2.创建订单
                        handleVoucherOrder(voucherOrder);
                    } catch (Exception e) {
                        log.error("处理订单异常", e);
                    }
                }
            }
        }
        private void handleVoucherOrder(VoucherOrder voucherOrder) {
            //1.获取用户
            Long userId = voucherOrder.getUserId();
            // 2.创建锁对象
            RLock redisLock = redissonClient.getLock("lock:order:" + userId);
            // 3.尝试获取锁
            boolean isLock = redisLock.tryLock();
            // 4.判断是否获得锁成功
            if (!isLock) {
                // 获取锁失败，直接返回失败或者重试
                log.error("不允许重复下单！");
                return;
            }
            try {
                //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy.createVoucherOrder(voucherOrder);
            } finally {
                // 释放锁
                redisLock.unlock();
            }
        }*/
    // 创建订单
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();
        // 创建锁对象
        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
        // 尝试获取锁
        boolean isLock = redisLock.tryLock();
        // 判断
        if (!isLock) {
            // 获取锁失败，直接返回失败或者重试
            log.error("不允许重复下单！");
            return;
        }
        try {
            // 5.1.查询订单
            int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            // 5.2.判断是否存在
            if (count > 0) {
                // 用户已经购买过了
                log.error("不允许重复下单！");
                return;
            }
            // 6.扣减库存
            boolean success = seckillVoucherService.update()
                    .setSql("stock = stock - 1") // set stock = stock - 1
                    .eq("voucher_id", voucherId).gt("stock", 0) // where id = ? and stock > 0
                    .update();
            if (!success) {
                // 扣减失败
                log.error("库存不足！");
                return;
            }
            // 7.创建订单
            save(voucherOrder);
        } finally {
            // 释放锁
            redisLock.unlock();
        }
    }

    /**
     * 抢秒杀券
     * @param voucherId
     * @return
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        // 获取用户
        Long userId = UserHolder.getUser().getId();
        // 获取订单Id
        long orderId = redisIdWorker.nextId("order");
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(),String.valueOf(orderId)
        );
        // 避免result为空值
        int r = Objects.requireNonNull(result).intValue();
        // 2.判断结果是否为0
        if (r != 0) {
            // 2.1.不为0 ，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        // 3.获取代理对象
        proxy = (IVoucherOrderService)AopContext.currentProxy();
        // 4.返回订单id
        return Result.ok(orderId);
    }

    /*@Override
    public Result seckillVoucher(Long voucherId) {
        // 获取用户
        Long userId = UserHolder.getUser().getId();
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        int r = result.intValue();
        // 2.判断结果是否为0
        if (r != 0) {
            // 2.1.不为0 ，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        VoucherOrder voucherOrder = new VoucherOrder();
        // 2.3.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 2.4.用户id
        voucherOrder.setUserId(userId);
        // 2.5.代金券id
        voucherOrder.setVoucherId(voucherId);
        // 2.6.放入阻塞队列
        orderTasks.add(voucherOrder);
        //3.获取代理对象
        proxy = (IVoucherOrderService)AopContext.currentProxy();
        //4.返回订单id
        return Result.ok(orderId);
    }*/

    /*@Override
    public Result seckillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀尚未开始！");
        }
        // 3.判断秒杀是否结束
        if(voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 已经结束
            return Result.fail("秒杀已经结束！");
        }
        // 4.判断库存是否充足
        if (voucher.getStock() < 1) {
            //库存不足
            return Result.fail("库存不足");
        }

        //Redis分布式锁
        Long userId = UserHolder.getUser().getId();
        //创建锁对象 这个代码不用了，因为我们现在要使用分布式锁
        //SimpleRedisLock lock = new SimpleRedisLock("order:" + userId,stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //获取锁对象
        boolean isLock = lock.tryLock();
        //加锁失败
        if (!isLock) {
            return Result.fail("不允许重复下单");
        }
        try {
            //获取代理对象（事务）
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            //释放锁
            lock.unlock();
        }

        /* 加悲观锁
        synchronized (userId.toString().intern()) {
            // 获取代理对象（事务）-确保事务生效
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        }*
    }*/

    /**
     * Ctrl+Alt+m:生成方法
     * @param voucherId
     * @return
     */
    /*@Override
    @Transactional
    public Result createVoucherOrder(Long voucherId) {
        // 5.一人一单逻辑
        // 5.1.从线程中取用户id
        Long userId = UserHolder.getUser().getId();
        // 5.2.查询订单
        int count = query().eq("user_id",userId).eq("voucher_id",voucherId).count();
        // 5.3.判断是否存在
        if (count > 0) {
            // 用户已经购买过了
            return Result.fail("用户已经购买过一次了！");
        }
        // 6.扣减库存
        // set stock = stock -1 where id = ? and stock > 0 大于0解决超卖问题
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherId).gt("stock", 0)
                .update();
        if(!success) {
            // 扣减失败
            return Result.fail("库存不足");
        }
        // 7.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        // 7.1.插入订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 7.2.插入用户id
        voucherOrder.setUserId(userId);
        // 7.3.插入代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        // 8.返回订单id
        return Result.ok(orderId);
    }*/
}
